1. Field of the Invention
The present invention relates to a dishwasher.
2. Discussion of the Related Art
Generally, a dishwasher is an apparatus for automatically washing and drying tableware by injecting water and detergent on the tableware. A dishwasher according to a related art is explained by referring to the attached drawings.
FIG. 1 is a cross-sectional view of a dishwasher according to a related art.
Referring to FIG. 1, a dishwasher according to a related art mainly consists of a cabinet 2 having a large open front side, a washing chamber 4 provided in the cabinet 2, and a door 6 opening closing the open front side of the cabinet 2.
Upper and lower racks 8 and 9 on which tableware is put are provided in the washing chamber 4, and top and bottom nozzles 12 and 14 injecting water via injection holes 10 are rotatably provided under the upper and lower racks 8 and 9, respectively.
A sump 16 is provided under the washing chamber 4 to collect water therein. A pump 24 connected to a supply pipe 22 is provided at one side of the sump 16 to pump water to the top and bottom nozzles 12 and 14. And, a heater assembly (not shown in the drawing) for heating water held in the sump 16 is provided in the sump 16.
The supply pipe 22 is connected to upper and lower pipes 26 and 28 guiding water to the top and bottom nozzles 12 and 14, respectively. Hence, when the pump 24 operates, the water in the sump 16 is supplied to the top and bottom nozzles 12 and 14 via the supply pipe 22 and the upper and lower pipes 26 and 28. Inlet valve and pipe for supplying water to the sump 16 and drain pump assembly and pipe for draining the water in the sump are installed at one side of the sump 16.
And, a filter 18 is installed over the sump 16 to filter the water flowing in the sump 16 from the washing chamber 4 to remove particles from the water.
Meanwhile, a valve assembly 30 for electrically opening/closing the upper and lower pipes 26 and 28 is installed at a portion where the upper and lower pipes 26 and 28 are connected to the supply pipe 22 to selectively allow the water flow in.
FIG. 2 is a cross-sectional view of a valve assembly of a dishwasher according to a related art.
Referring to FIG. 2, the valve assembly 30 consists of protrusions 32a and 32b formed inside the upper and lower pipes 26 and 28, respectively, a pair of check valves 34a and 34b and a pair of solenoid valves 36a and 36b. 
The check valves 34a and 34b are movably installed in the upper and lower pipes 26 and 28 to open/close the upper and lower pipes 26 and 28, respectively. And, the solenoid valves 36a and 36b are installed under the check valves 34a and 34b to turn on/off the check valves 34a and 34b by magnetic forces, respectively.
Of course, the check valves 34a and 34b are magnetic bodies movable by the magnetic forces on operating the solenoid valves 36a and 36b, respectively.
An operation of the related art dishwasher is explained in short as follows.
First of all, once the pump 24 is driven, the check valves 34a and 34b are moved upward by the water flowing in via the supply pipe 22 to be brought contact with the protrusions 32a and 32b, respectively. Hence, the check valves 34a and 34b blocks the upper and lower pipes 26 and 28 to prevent the water from flowing in the upper and lower pipes 26 and 28, respectively.
Thereafter, once a pair of the solenoid valves 36a and 36b are driven, the check valves 34a and 34b move downward by the magnetic forces to open the upper and lower pipes 26 and 28, respectively. Hence, the water is supplied to the top and bottom nozzles 12 and 14 via the upper and lower pipes 26 and 28, respectively.
Yet, when both of the upper and lower pipes 26 and 28 are open by driving a pair of the solenoid valves 36a and 36b simultaneously, the water is supplied to the top and bottom nozzles 12 and 14 along the upper and lower pipes 26 and 28, respectively so that the water pressures and injection powers thereof are lowered. Hence, the solenoid valves 36a and 36b are selectively operated to supply the water via either the upper or lower pipe 26 or 28.
However, in the related art dishwasher, the magnetic check valves are provided in the upper and lower pipes and the check valves are turned on/off by the expensive solenoid valves, respectively, whereby product costs are increased.
Moreover, since the solenoid valves are electrically driven, electric safety accident may take place as well as power consumption thereof increases.